"In fact I believe the fan shroud actually impedes the free air flow a little at speed "
I think your right.It looks like you gain 10* on the highway.
But you are still at 200*,even after the tests being run in over 15* warmer ambient tempts.80* vs 96*.
I think you started out with 210* idle with tempts in mid 80's.
No telling what it would be at 96*.
